1. Field of the Invention
The present invention relates to a tentering device, and more particularly to a tentering device wherein the spreading width of a cloth can be easily changed during the cloth spreading process without need of stopping the equipment in use.
2. Description of the Prior Art
Heretofore, various types of tentering devices have been used with the aim of spreading cloth to a predetermined width thereby to obtain products of uniform quality.
One such type of tentering device is the clip-type spreading device or the pin-tenter device which has clamps or pins mounted on each of a pair of generally parallel side chains. These clamps or pins clamp or hook the opposite selvages of a cloth fed from a feeding roller so that the cloth is spread to a predetermined width as the clamps or pins are moved and guided by the sidechains. The cloth spreading width is predetermined by setting the distance between the side chains on which the clamps or pins are mounted. Such prior art devices cannot immediately vary the spreading width in the course of the cloth spreading process. Since the sidechains and hence the pins or clamps cannot move in the defective portion, for example, a narrow portion in the cloth to be tentered, the narrow portion is overstretched with the frequent result that it is torn.
Another type of tentering device is the calendar machine. The calendar machine is constructed in such manner that a cloth of, for example, tubular configuration, passed between heated rollers is thereafter passed over a fixed width spreader of, for example, U-shaped configuration. That is to say, in use, the spreader is inserted into the tubular cloth. As with the aforementioned clip-type or pin-type spreading device, this type of tentering device is adjusted for spreading width prior to use and therefore cannot be immediately varied in spreading width in the course of the spreading process. Moreover, the device overstretches narrow portions of the cloth and, in extreme cases, causes the cloth to tear.